It’s an old joke, referring to the idea of tracing a famous family back. Like if you found out someone was called Van Doren you might say “oh, is she of the New York Van Dorens?”. When you encounter a name like Chaos Grenade, you might speculate that Chaos is a first name and Grenade a last name, conjuring up an entire clan of Grenades. Obviously, the Texas line of the family aren’t related to the New York Grenades – John and Jane Grenade, descended from of course old Hyburn Grenade who came over on the Mayflower.